def METHOD_NAME(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_str(src, preamble_len=STANDARD_PREAMBLE_LEN, single_node=True)
  if __debug__:
    if not isinstance(node, gast.Expr):
      raise ValueError(
          'expected a single expression, found instead {}'.format(node))
  return node.value