>>> incl_plus = True
>>> val = 1
>>> _get_sign(val, incl_plus)
'+'
>>> incl_plus = False
>>> _get_sign(val, incl_plus)
''
>>> val = -1
>>> _get_sign(val, incl_plus)
'-'
>>> incl_plus = True
>>> _get_sign(val, incl_plus)
'-'
>>> val = 0
>>> _get_sign(val, incl_plus)
'+'
>>> incl_plus = False
>>> _get_sign(val, incl_plus)
''
