class_docstr: A "copy" of a sequence that works by inserting a mask in front
  of the underlying sequence, so that you can mutate it without changing
  the underlying sequence. Effectively behaves as if you could do list(x)
  in O(1) time. The full list API is not supported yet but there's no reason
  in principle it couldn't be.
code: def __setitem__(self, i, v):
      i = self.__check_index(i)
      if self.__mask is None:
          self.__mask = {}
      self.__mask[i] = v
  
imports: from __future__ import absolute_import, division, print_function
  from hypothesis.internal.compat import array_or_list, hbytes, int_to_bytes, integer_types
label_desc: Use image node_id 5 for calling the LazySequenceCopy obj's underlying member method code with example usage: obj.__setitem__(i, v) without return types