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# Code Generation
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Commands for generating code from templates and managing template libraries to accelerate development and maintain consistency across projects.
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## Capabilities
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### Generate from Template
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Generate and scaffold files from a pre-defined template into the workspace.
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```bash { .api }
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moon generate <name> [dest] [--defaults] [--dry-run] [--force] [--template]
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```
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**Alias:** `moon g`
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**Arguments:**
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- `name` (required) - Name of the template to generate from
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- `dest` (optional) - Destination path relative to workspace root or working directory
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**Options:**
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- `--defaults` - Use default values for all template variables instead of prompting
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- `--dry-run` - Run the entire generation process without writing any files
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- `--force` - Force overwrite any existing files at the destination
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- `--template` - Create a new template instead of generating from an existing one
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**Usage Examples:**
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```bash
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# Generate using interactive prompts
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moon generate react-component
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# Generate to specific destination
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moon generate react-component ./src/components/NewComponent
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# Use short alias
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moon g nodejs-app ./apps/my-new-app
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# Use defaults without prompting
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moon generate typescript-library --defaults
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# Preview generation without creating files
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moon generate react-component --dry-run
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# Force overwrite existing files
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moon generate api-endpoint ./src/api/users --force
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# Create a new template
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moon generate my-template --template
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```
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### List Available Templates
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Display all templates available for code generation in the workspace.
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```bash { .api }
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moon templates [--filter <PATTERN>] [--json]
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```
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**Options:**
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- `--filter <PATTERN>` - Filter templates based on name or description pattern
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- `--json` - Output template information in JSON format
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**Usage Examples:**
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```bash
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# List all available templates
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moon templates
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# Filter templates by pattern
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moon templates --filter react
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# Get template info as JSON
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moon templates --json
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# Filter with wildcard pattern
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moon templates --filter "*-component"
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```
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**Sample Output:**
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```
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Templates:
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  react-component     Generate a React functional component with TypeScript
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  nodejs-api          Generate a Node.js API server with Express
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  typescript-library  Generate a TypeScript library package
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  nextjs-app          Generate a Next.js application
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  documentation       Generate documentation files and structure
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```
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## Template Structure
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Moon templates are organized in the `.moon/templates/` directory:
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```
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.moon/templates/
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├── react-component/
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│   ├── template.yml           # Template configuration
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│   ├── {{name}}.tsx          # Component file template  
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│   ├── {{name}}.test.tsx     # Test file template
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│   └── index.ts              # Export file template
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├── nodejs-api/
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│   ├── template.yml
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│   ├── src/
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│   │   ├── app.ts
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│   │   └── routes/
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│   ├── package.json
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│   └── README.md
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└── shared/                   # Shared template partials
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    ├── license.txt
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    └── gitignore.txt
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```
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## Template Configuration
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Templates are configured using `template.yml`:
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```yaml
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# Example template.yml
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name: "React Component"
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description: "Generate a React functional component with TypeScript"
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destination: "src/components"
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variables:
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  - name: "name"
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    description: "Component name"
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    type: "string"
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    required: true
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  - name: "withTests"
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    description: "Include test files"
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    type: "boolean"
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    default: true
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  - name: "styling"
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    description: "Styling approach"
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    type: "enum"
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    options: ["css-modules", "styled-components", "tailwind"]
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    default: "css-modules"
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files:
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  - source: "{{name}}.tsx"
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    destination: "{{name}}/{{name}}.tsx"
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  - source: "{{name}}.test.tsx"
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    destination: "{{name}}/{{name}}.test.tsx"
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    condition: "{{withTests}}"
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  - source: "index.ts"
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    destination: "{{name}}/index.ts"
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```
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## Template Variables
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Templates support various variable types:
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- **String** - Text input from user
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- **Boolean** - Yes/no questions
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- **Enum** - Select from predefined options
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- **Number** - Numeric input
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- **Array** - Multiple values
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Variables can be used in:
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- File names (e.g., `{{name}}.tsx`)
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- File contents (e.g., `export const {{name}} = () => {}`)
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- Directory names (e.g., `{{name}}/`)
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- Conditional file inclusion
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## Template Syntax
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Moon uses Handlebars-style templating:
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```typescript
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// In template file: {{name}}.tsx
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import React from 'react';
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{{#if withTests}}
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import { render } from '@testing-library/react';
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{{/if}}
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interface {{name}}Props {
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  {{#each props}}
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  {{name}}: {{type}};
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  {{/each}}
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}
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export const {{name}}: React.FC<{{name}}Props> = ({
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  {{#each props}}{{name}},{{/each}}
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}) => {
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  return (
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    <div className="{{kebabCase name}}">
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      {/* {{description}} */}
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    </div>
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  );
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};
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{{#if withTests}}
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// Test file content
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describe('{{name}}', () => {
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  it('renders correctly', () => {
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    render(<{{name}} />);
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  });
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});
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{{/if}}
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```
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## Helper Functions
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Templates include built-in helper functions:
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- `{{camelCase text}}` - Convert to camelCase
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- `{{pascalCase text}}` - Convert to PascalCase  
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- `{{kebabCase text}}` - Convert to kebab-case
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- `{{snakeCase text}}` - Convert to snake_case
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- `{{upperCase text}}` - Convert to UPPER_CASE
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- `{{lowerCase text}}` - Convert to lower case
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## Creating Custom Templates
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```bash
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# Create a new template interactively
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moon generate my-template --template
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# Manual template creation
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mkdir .moon/templates/my-template
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touch .moon/templates/my-template/template.yml
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# Edit template.yml with configuration
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# Add template files with variable placeholders
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```
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## Template Sharing
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Templates can be shared across projects:
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```bash
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# Export template
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moon templates export react-component > react-component.tar.gz
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# Import template
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moon templates import react-component.tar.gz
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# Sync templates from remote repository
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moon templates sync --from https://github.com/company/moon-templates
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```
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## Best Practices
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### Template Organization
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- Group related templates in logical categories
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- Use descriptive names and documentation
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- Include example usage in template descriptions
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- Version control templates with the workspace
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### Variable Design
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- Use clear, descriptive variable names
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- Provide sensible defaults where possible
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- Include help text for complex options
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- Validate user input when necessary
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### File Structure
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- Follow consistent naming conventions
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- Include necessary configuration files
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- Provide complete, working examples
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- Include appropriate documentation and comments