code: def nameprep(label):
      # Map
      newlabel = []
      for c in label:
          if stringprep.in_table_b1(c):
              # Map to nothing
              continue
          newlabel.append(stringprep.map_table_b2(c))
      label = "".join(newlabel)
  
      # Normalize
      label = unicodedata.normalize("NFKC", label)
  
      # Prohibit
      for c in label:
          if (
              stringprep.in_table_c12(c)
              or stringprep.in_table_c22(c)
              or stringprep.in_table_c3(c)
              or stringprep.in_table_c4(c)
              or stringprep.in_table_c5(c)
              or stringprep.in_table_c6(c)
              or stringprep.in_table_c7(c)
              or stringprep.in_table_c8(c)
              or stringprep.in_table_c9(c)
          ):
              raise UnicodeError("Invalid character %r" % c)
  
      # Check bidi
      RandAL = [stringprep.in_table_d1(x) for x in label]
      if any(RandAL):
          # There is a RandAL char in the string. Must perform further
          # tests:
          # 1) The characters in section 5.8 MUST be prohibited.
          # This is table C.8, which was already checked
          # 2) If a string contains any RandALCat character, the string
          # MUST NOT contain any LCat character.
          if any(stringprep.in_table_d2(x) for x in label):
              raise UnicodeError("Violation of BIDI requirement 2")
          # 3) If a string contains any RandALCat character, a
          # RandALCat character MUST be the first character of the
          # string, and a RandALCat character MUST be the last
          # character of the string.
          if not RandAL[0] or not RandAL[-1]:
              raise UnicodeError("Violation of BIDI requirement 3")
  
      return label
  
imports: import stringprep, re, codecs
  from unicodedata import ucd_3_2_0
label_desc: Use image node_id 1 for calling a global function with example usage: nameprep(label) and returns: label