[PyMOL] Where can I find the definition of class Atom and Bond ?

[Xiao Jianfeng]

Hello,

I saw "from chempy import Storage, Atom, Bond" in pymol source files.

I can import chempy Atom successfully, but where can I find the
defeintion of class Atom and bond ? I tried to print
chempy.Atom.__file__, but it didn't work.

Thanks.