class_docstr: Implements `RateCurve` class using discounting function.
code: def __init__(
      self, maturity_dates, rates, valuation_date, discount_fn, dtype
  ):
      super(RateCurveFromDiscountingFunction, self).__init__(
          maturity_dates, rates, valuation_date, dtype=dtype
      )
      self._discount_fn = discount_fn
  
file_path: tf-quant-finance/tf_quant_finance/experimental/instruments/rate_curve.py
imports: import tensorflow.compat.v2
  from tf_quant_finance import datetime
  from tf_quant_finance.math.interpolation import linear
label_desc: Use image node_id 1 to create a new RateCurveFromDiscountingFunction object from inherited base classes: RateCurve with example: obj = RateCurveFromDiscountingFunction(maturity_dates, rates, valuation_date, discount_fn, dtype)