How to use the wand.assertions.string_in_list function in Wand

def gravity(self, value):
        assertions.string_in_list(GRAVITY_TYPES,
                                  'wand.drawing.GRAVITY_TYPES',
                                  gravity=value)
        library.DrawSetGravity(self.resource, GRAVITY_TYPES.index(value))

This method has been replace by :meth:`alpha()` in ImageMagick
            version 7. An :class:`AttributeError` will be raised if attempting
            to call on a library without ``DrawMatte`` support.

        .. versionadded:: 0.4.0

        """
        if library.DrawMatte is None:
            raise AttributeError(
                'Method removed from ImageMagick version. ' +
                'Please use `wand.drawing.Drawing.alpha()\' instead.'
            )
        if x is None or y is None:
            raise TypeError('Both x & y coordinates need to be defined')
        assertions.string_in_list(PAINT_METHOD_TYPES,
                                  'wand.drawing.PAINT_METHOD_TYPES',
                                  paint_method=paint_method)
        library.DrawMatte(self.resource, float(x), float(y),
                          PAINT_METHOD_TYPES.index(paint_method))

def text_direction(self, direction):
        if library.DrawGetTextDirection is None:  # pragma: no cover
            raise WandLibraryVersionError(
                'The installed version of ImageMagick does not support '
                'this feature'
            )
        assertions.string_in_list(TEXT_DIRECTION_TYPES,
                                  'wand.drawing.TEXT_DIRECTION_TYPES',
                                  text_direction=direction)
        library.DrawSetTextDirection(self.resource,
                                     TEXT_DIRECTION_TYPES.index(direction))

def text_alignment(self, align):
        assertions.string_in_list(TEXT_ALIGN_TYPES,
                                  'wand.drawing.TEXT_ALIGN_TYPES',
                                  text_alignment=align)
        library.DrawSetTextAlignment(self.resource,
                                     TEXT_ALIGN_TYPES.index(align))

def font_style(self, style):
        assertions.string_in_list(STYLE_TYPES,
                                  'wand.drawing.STYLE_TYPES',
                                  font_style=style)
        library.DrawSetFontStyle(self.resource,
                                 STYLE_TYPES.index(style))

def fill_rule(self, fill_rule):
        assertions.string_in_list(FILL_RULE_TYPES,
                                  'wand.drawing.FILL_RULE_TYPES',
                                  fill_rule=fill_rule)
        library.DrawSetFillRule(self.resource,
                                FILL_RULE_TYPES.index(fill_rule))

def font_stretch(self, stretch):
        assertions.string_in_list(STRETCH_TYPES,
                                  'wand.drawing.STRETCH_TYPES',
                                  font_stretch=stretch)
        library.DrawSetFontStretch(self.resource,
                                   STRETCH_TYPES.index(stretch))

def clip_units(self, clip_unit):
        assertions.string_in_list(CLIP_PATH_UNITS,
                                  'wand.drawing.CLIP_PATH_UNITS',
                                  clip_unit=clip_unit)
        library.DrawSetClipUnits(self.resource,
                                 CLIP_PATH_UNITS.index(clip_unit))

def stroke_line_cap(self, line_cap):
        assertions.string_in_list(LINE_CAP_TYPES,
                                  'wand.drawing.LINE_CAP_TYPES',
                                  stroke_line_cap=line_cap)
        library.DrawSetStrokeLineCap(self.resource,
                                     LINE_CAP_TYPES.index(line_cap))