docs: 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)