code: def __to_float64(self, x):
      x_dtype = x.dtype
      assert x_dtype in ["float32", "float64"]
      x = x.astype("float64")
      return x
  
imports: import pymatting
  from paddleseg.cvlibs import manager
label_desc: Use image node_id 3 for calling the BaseMLMatting obj's underlying member method code with example usage: obj.__to_float64(x) and returns: x