def getOverlayImage(self, retina_name, body, plot_shape="circle", image_scalar=2, image_encoding="base64/png"):

        resourcePath = '/image/compare'
        method = 'POST'

        queryParams = {}
        headerParams = {'Accept': 'image/png', 'Content-Type': 'application/json'}
        postData = None

        queryParams['retina_name'] = retina_name
        queryParams['plot_shape'] = plot_shape
        queryParams['image_scalar'] = image_scalar
        queryParams['image_encoding'] = image_encoding
        postData = body
        
        response = self.apiClient._callAPI(resourcePath, method, queryParams, postData, headerParams)
        return response.content
Prove that _format_header correctly formats text input.
dataset/ETHPy150Open cortical-io/python-client-sdk/cortical/imageApi.py/ImageApi.getOverlayImage--crossover with--dataset/ETHPy150Open sigmavirus24/requests-toolbelt/tests/test_dump.py/TestSimplePrivateFunctions.test_format_header_handles_unicode