code: def _init_api(namespace, target_module_name=None):
      """Initialize api for a given module name
  
      namespace : str
         The namespace of the source registry
  
      target_module_name : str
         The target module name if different from namespace
      """
      target_module_name = (
          target_module_name if target_module_name else namespace
      )
      if namespace.startswith("dgl."):
          return _init_api_prefix(target_module_name, namespace[4:])
      else:
          return _init_api_prefix(target_module_name, namespace)
  
imports: from __future__ import absolute_import
  import ctypes
  import sys
  from .base import _FFI_MODE, _LIB, c_str, check_call, py_str, string_types
label_desc: Use image node_id 6 for calling a global function with example usage: _init_api(namespace, target_module_name) and returns: _init_api_prefix, _init_api_prefix