Errors

Review [PEP 257](https://www.python.org/dev/peps/pep-0257/) for docstring formatting. Docstrings should either be a single line phrase that ends in a period and expresses a command, or a multi-line docstring that consists of a summary line, followed by a blank line and a more detailed description. Per [PEP 8](https://www.python.org/dev/peps/pep-0008/#maximum-line-length), docstrings can be up to 72 characters.