code: def U(name):
      """
      Get a unicode character by name or, None if not found.
  
      This exists because older versions of Python use older unicode databases.
      """
      try:
          return unicodedata.lookup(name)
      except KeyError:
          global unicode_warnings
          unicode_warnings += "No '%s' in unicodedata\n" % name
          return None
  
imports: import sys
  import warnings
  from string import ascii_lowercase, ascii_uppercase
  import unicodedata
  from sympy.printing.conventions import split_super_sub
  from sympy.core.alphabets import greeks
  from sympy.utilities.exceptions import sympy_deprecation_warning
label_desc: Use image node_id 1 for calling a global function with example usage: U(name) and returns: unicodedata, None