def describe_deployments(StackId=None, AppId=None, DeploymentIds=None):
    """
    Requests a description of a specified set of deployments.
    See also: AWS API Documentation
    
    
    :example: response = client.describe_deployments(
        StackId='string',
        AppId='string',
        DeploymentIds=[
            'string',
        ]
    )
    
    
    :type StackId: string
    :param StackId: The stack ID. If you include this parameter, DescribeDeployments returns a description of the commands associated with the specified stack.

    :type AppId: string
    :param AppId: The app ID. If you include this parameter, DescribeDeployments returns a description of the commands associated with the specified app.

    :type DeploymentIds: list
    :param DeploymentIds: An array of deployment IDs to be described. If you include this parameter, DescribeDeployments returns a description of the specified deployments. Otherwise, it returns a description of every deployment.
            (string) --
            

    :rtype: dict
    :return: {
        'Deployments': [
            {
                'DeploymentId': 'string',
                'StackId': 'string',
                'AppId': 'string',
                'CreatedAt': 'string',
                'CompletedAt': 'string',
                'Duration': 123,
                'IamUserArn': 'string',
                'Comment': 'string',
                'Command': {
                    'Name': 'install_dependencies'|'update_dependencies'|'update_custom_cookbooks'|'execute_recipes'|'configure'|'setup'|'deploy'|'rollback'|'start'|'stop'|'restart'|'undeploy',
                    'Args': {
                        'string': [
                            'string',
                        ]
                    }
                },
                'Status': 'string',
                'CustomJson': 'string',
                'InstanceIds': [
                    'string',
                ]
            },
        ]
    }
    
    
    :returns: 
    execute_recipes : Execute one or more recipes. To specify the recipes, set an Args parameter named recipes to the list of recipes to be executed. For example, to execute phpapp::appsetup , set Args to {"recipes":["phpapp::appsetup"]} .
    install_dependencies : Install the stack's dependencies.
    update_custom_cookbooks : Update the stack's custom cookbooks.
    update_dependencies : Update the stack's dependencies.
    
    """
    pass
