code: def getenv(name):
      """Get the setting of an environment variable from the C Runtime.
  
      Parameters
      ----------
      name : string type
          The environment variable name
  
      Returns
      -------
      value : string
          The value of the environment variable, or None if not set
      """
      ret = ctypes.c_char_p()
      check_call(_LIB.MXGetEnv(c_str(name), ctypes.byref(ret)))
      return None if ret.value is None else py_str(ret.value)
  
imports: import ctypes
  import functools
  import inspect
  import threading
  import tempfile
  import platform
  from contextlib import contextmanager
  from struct import calcsize
  from .base import _LIB, check_call, c_str, py_str, numeric_types, integer_types, long, _MAX_VALUE_64_BIT_UNSIGNED_, _MAX_VALUE_64_BIT_SIGNED_, _MAX_VALUE_FLOAT32_REPRESENT_
label_desc: Use image node_id 30 for calling a global function with example usage: getenv(name) and returns: unknown