code: def loads(content):
      
      lines = _group_lines(line for line in content.split('\n'))
      lines = [
          (i, _parse_envfile_line(line))
          for i, line in lines if line.strip()
      ]
      errors = []
      # Reject files with duplicate variables (no sane default).
      duplicates = _find_duplicates(((i, line[0]) for i, line in lines))
      for i, variable, j in duplicates:
          errors.append(''.join([
                  'Line %d: duplicate environment variable "%s": ',
                  'already appears on line %d.',
              ]) % (i + 1, variable, j + 1)
          )
      # Done!
      if errors:
          raise ValueError(errors)
      return {k: v for _, (k, v) in lines}
docs: Loads variable definitions from a string.