code: def parse_expression(src):
      """Returns the AST of given identifier.
  
      Args:
        src: A piece of code that represents a single Python expression
      Returns:
        A gast.AST object.
      Raises:
        ValueError: if src does not consist of a single Expression.
      """
      src = STANDARD_PREAMBLE + src.strip()
      node = parse(
          src, preamble_len=STANDARD_PREAMBLE_LEN, single_node=True
      )
      if __debug__:
          if not isinstance(node, gast.Expr):
              raise ValueError(
                  "expected exactly one node of type Expr, got {}".format(
                      node
                  )
              )
      return node.value
  
imports: import ast
  import inspect
  import linecache
  import re
  import sys
  import textwrap
  import tokenize
  import astunparse
  import gast
  import six
  from nvidia.dali._autograph.pyct import errors
  from nvidia.dali._autograph.pyct import inspect_utils
label_desc: Use image node_id 9 for calling a global function with example usage: parse_expression(src) and returns: node