class_docstr: This class wraps peak memory usage in a way that pretends to be a clock.
  
  The __sub__ (-) operator ignores the "before" argument, because this assumes that each peak
  recorded independently, by calling `tracemalloc.clear_traces()` to reset the traces.
code: def __init__(self, peak: int):
      self._peak = peak
  
file_path: stellargraph/tests/test_utils/alloc.py
imports: import gc
  import pytest
  import tracemalloc
label_desc: Use image node_id 1 to create a new MallocPeak object  with example: obj = MallocPeak(peak)