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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def _get_imagesave_wildcards(self):
        'return the wildcard string for the filesave dialog'
        default_filetype = self.get_default_filetype()
        filetypes = self.get_supported_filetypes_grouped()
        sorted_filetypes = filetypes.items()
        sorted_filetypes.sort()
        wildcards = []
        extensions = []
        filter_index = 0
        for i, (name, exts) in enumerate(sorted_filetypes):
            ext_list = ';'.join(['*.%s' % ext for ext in exts])
            extensions.append(exts[0])
            wildcard = '%s (%s)|%s' % (name, ext_list, ext_list)
            if default_filetype in exts:
                filter_index = i
            wildcards.append(wildcard)
        wildcards = '|'.join(wildcards)
        return wildcards, extensions, filter_index