r"""Adds primary key to database table

    Parameters
    ----------
    conn : sqlalchemy connection object
        A valid connection to a database
    schema : str
        The database schema
    table : str
        The database table
    pk_col : str
        Column that primary key is applied to

def add_primary_key(conn, schema, table, pk_col):
    r"""Adds primary key to database table

    Parameters
    ----------
    conn : sqlalchemy connection object
        A valid connection to a database
    schema : str
        The database schema
    table : str
        The database table
    pk_col : str
        Column that primary key is applied to

    """
    sql_str = """alter table {schema}.{table} add primary key ({col})""".format(
        schema=schema, table=table, col=pk_col)

    conn.execute(sql_str)