code: def defines_to_dict(defines):
      
      if defines is None:
          return None
      result = {}
      for define in defines:
          kv = define.split('=', 1)
          if len(kv) == 1:
              result[define.strip()] = 1
          else:
              result[kv[0].strip()] = kv[1].strip()
      return result
docs: Convert a list of definition strings to a dictionary.