docstrings for tmpo-py

[saroele]

I vote for docstrings in tmpo-py. Now, some functions are unclear to me. We can write the docstrings while working on the unittest, both go hand-in-hand.

For docstrings, the following format is normally rendered well by most tools

def myfunc(self, arg1, arg2=200):
    """
    One line to describe what the function does

    Parameters
    ---------------
    * arg1 : Type of arg1
        Description of arg1 
    * arg2 : Integer (default=200)
        Description of arg2

    Returns  
    ----------
    res : type and description

    Raises
    ----------
    this is optional: a description of exceptions that can be raised

    Notes
    ----------
    A longer description of the function, with notes for using, implementation, details, etc. 
    """