code: def test_print_bars_mixed_signs(self):
      rows = (("-1.7", 2, "a"), ("11.18", None, None), ("0", 1, "c"))
  
      table = Table(rows, self.column_names, self.column_types)
      table.print_bars("three", "one")
  
file_path: agate/tests/test_table/test_print_bars.py
imports: from io import StringIO
  from babel.numbers import format_decimal
  from agate import Table
  from agate.data_types import Number, Text
  from agate.exceptions import DataTypeError
  from agate.testcase import AgateTestCase
label_desc: Use image node_id 8 for calling the TestPrintBars obj's underlying member method code with example usage: obj.test_print_bars_mixed_signs() without return types