docs: def _normal_function(x, mean, variance):
      """
      Find a value in the cumulative distribution function of a normal curve.
  
      See https://en.wikipedia.org/wiki/Normal_distribution
  
      Args:
          x (float): Value to feed into the normal function
          mean (float): Mean of the normal function
          variance (float): Variance of the normal function
  
      Returns: float
  
      Example:
          >>> round(_normal_function(0, 0, 5), 4)
          0.1784
      """
      e_power = -1 * (((x - mean) ** 2) / (2 * variance))
      return (1 / math.sqrt(2 * variance * math.pi)) * (math.e ** e_power)