code: def get_atom_mass(atom_z: int) -> float:
      """Returns the Atomic mass in Atomic Mass Unit.
  
      Examples
      --------
      >>> from deepchem.utils import get_atom_mass
      >>> atom_number = 13
      >>> get_atom_mass(atom_number)
      49184.33860618758
  
      Parameters
      ----------
      atom_z: int
          Atomic Number of the Element.
  
      Returns
      -------
      atomic_mass: float
          Atomic Mass of the Element.
  
      References
      ----------
      Kasim, Muhammad F., and Sam M. Vinko. "Learning the exchange-correlation
      functional from nature with fully differentiable density functional
      theory." Physical Review Letters 127.12 (2021): 126403.
      https://github.com/diffqc/dqc/blob/master/dqc/utils/periodictable.py
  
      """
      try:
          atomic_mass = atom_masses[atom_z]
      except KeyError:
          raise KeyError(
              "Element Does Not Exists or Not Documented: %d" % atom_z
          )
  
      return atomic_mass * 1822.888486209
  
imports: from typing import Union
  import numpy
  import torch
label_desc: Use image node_id 2 for calling a global function with example usage: get_atom_mass(atom_z) and returns: unknown