code: def uni_char_code(a, b, c, d):
      """Converts four hexidecimal chars to the integer that the
      string represents. For example, uniCharCode('0','0','0','f')
      will return 15, and uniCharCode('0','0','f','f') returns 255.
  
      Returns a negative number on error, if a char was invalid.
  
      This is implemented by noting that char2hex() returns -1 on error,
      which means the result of ORing the char2hex() will also be negative.
      """
      return (
          char2hex(a) << 12
          | char2hex(b) << 8
          | char2hex(c) << 4
          | char2hex(d)
      )
  
imports: import json
  from ..error import GraphQLSyntaxError
label_desc: Use image node_id 10 for calling a global function with example usage: uni_char_code(a, b, c, d) and returns: unknown