Add type hints to functions in python scripts

[hechth]

Type hints in python serve as a hint to the integrated development environment (IDE) which type a function parameter or variable can have and makes it then easier for developers to figure out how this variable can be used. Functions should also receive return type annotations to indicate what is actually returned by the function.

Detailed description of type hints in python and how they can be validated is available here.

Files in which to add functions:

• analysis/Python_scripts/utils.py
• analysis/Python_scripts/plotting.py
• codes/extract_coords_into_inp_xyz.py
• codes/write_dirs_files_for_gamess_qcxms.py