docstr: Returns the registered custom source files.
  
  Returns:
      dict: Custom source files. Keys represent destination paths, values are absolute paths to registered source
          files.
docstr_tok: ["Returns","the","registered","custom","source","files",".","Returns",":","dict",":","Custom","source","files",".","Keys","represent","destination","paths",",","values","are","absolute","paths","to","registered","source","files","."]
code: def get_custom_source(self):
      """Returns the registered custom source files.
  
      Returns:
          dict: Custom source files. Keys represent destination paths, values are absolute paths to registered source
              files.
      """
      return self.custom_source
  
imports: import inspect
  import os
  from pathlib import Path
  from hls4ml.backends.template import Template
  from hls4ml.model.flow import get_backend_flows, update_flow
  from hls4ml.model.optimizer import LayerOptimizerPass, extract_optimizers_from_object, extract_optimizers_from_path, get_backend_passes, get_optimizer, register_pass
label_desc: Use image node_id 11 for calling the Backend obj's underlying member method code with example usage: obj.get_custom_source() and returns: self