def calculate_price(weight, price_per_pound=1.5, tax=0.15):
"""Calculate price for a amount
weight -- weight expressed in pounds
price_per_pound -- price paid per one pound
tax -- the tax value that needs to the price
return weight * price_per_pound * (1+tax)
In Python, anything put between
""" will be treated as a documentation string for a given function. Note where we placed the documentation: it comes right after the line beginning with
def function_name, and is indented together with the function body.
Documentation strings (or docstrings) are a convenient way to provide documentation for a function: what it does, what parameters it expects, etc.