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 __sub__(self, other: "MallocPeak") -> int:
      return self._peak
  
file_path: stellargraph/tests/test_utils/alloc.py
imports: import gc
  import pytest
  import tracemalloc
label_desc: Use image node_id 2 for calling the MallocPeak obj's underlying member method code with example usage: obj.__sub__(other) and returns: self