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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def list_documents(project_id, knowledge_base_id):
 """Lists the Documents belonging to a Knowledge base. Args: project_id: The GCP project linked with the agent. knowledge_base_id: Id of the Knowledge base."""

    import dialogflow_v2beta1 as dialogflow
    client = dialogflow.DocumentsClient()
    knowledge_base_path = client.knowledge_base_path(project_id,
                                                     knowledge_base_id)

    print('Documents for Knowledge Id: {}'.format(knowledge_base_id))
    for document in client.list_documents(knowledge_base_path):
        print(' - Display Name: {}'.format(document.display_name))
        print(' - Knowledge ID: {}'.format(document.name))
        print(' - MIME Type: {}'.format(document.mime_type))
        print(' - Knowledge Types:')
        for knowledge_type in document.knowledge_types:
            print('    - {}'.format(KNOWLEDGE_TYPES[knowledge_type]))
        print(' - Source: {}\n'.format(document.content_uri))