! @brief Search the project directory for a file.

def find_user_file(self, option_name, filename_list):
        """! @brief Search the project directory for a file."""
        if option_name is not None:
            filePath = self._options.get(option_name, None)
        else:
            filePath = None
        
        # Look for default filenames if a path wasn't provided.
        if filePath is None:
            for filename in filename_list:
                thisPath = os.path.join(self.project_dir, filename)
                if os.path.isfile(thisPath):
                    filePath = thisPath
                    break
        # Use the path passed in options, which may be absolute, relative to the
        # home directory, or relative to the project directory.
        else:
            filePath = os.path.expanduser(filePath)
            if not os.path.isabs(filePath):
                filePath = os.path.join(self.project_dir, filePath)
        
        return filePath