docs: def get_length(self, length, trim=0, offset=0):
          """Return string at current position + length.
          If trim == true then get as much as possible before eos.
          """
          if trim and not self.has_space(offset + length):
              return self.string[self.pos + offset:]
          elif self.has_space(offset + length):
              return self.string[self.pos + offset:self.pos + offset + length]
          else:
              return ''