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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_conversion_type(self, convert_to=None):
        '''a helper function to return the conversion type based on user 
           preference and input recipe.

           Parameters
           ==========
           convert_to: a string either docker or singularity (default None)

        '''
        acceptable = ['singularity', 'docker']

        # Default is to convert to opposite kind
        conversion = "singularity"
        if self.name == "singularity":
            conversion = "docker"

        # Unless the user asks for a specific type
        if convert_to is not None and convert_to in acceptable:
            conversion = convert_to
        return conversion