class_docstr: Base class for defining arms.
  
  Randomization in experiments assigns units to a given arm. Thus, the arm
  encapsulates the parametrization needed by the unit.
code: def __hash__(self) -> int:
      return int(self.signature, 16)
  
imports: import hashlib
  import json
  from typing import Optional
  from ax.core.types import TParameterization
  from ax.utils.common.base import SortableBase
  from ax.utils.common.equality import equality_typechecker
  from ax.utils.common.typeutils import numpy_type_to_python_type
label_desc: Use image node_id 12 for calling the Arm obj's underlying member method code with example usage: obj.__hash__() and returns: int