code: def _init_fill_value(self, fill_value):
      if ivy.exists(fill_value):
          self._fill_value = ivy.array(fill_value, dtype=self._dtype)
      elif ivy.is_bool_dtype(self._dtype):
          self._fill_value = ivy.array(True)
      elif ivy.is_int_dtype(self._dtype):
          self._fill_value = ivy.array(999999, dtype="int64")
      else:
          self._fill_value = ivy.array(1e20, dtype="float64")
  
imports: import ivy
  import ivy.functional.frontends.numpy
  import numpy
label_desc: Use image node_id 4 for calling the MaskedArray obj's underlying member method code with example usage: obj._init_fill_value(fill_value) without return types