numeric = function numeric(value, outputType) {
    var inputType = getTypeOf(value);

    if (!(inputType in validInputTypes)) {
      throw new TypeError('Cannot convert ' + value + ' of type "' + inputType + '"; valid input types are ' + Object.keys(validInputTypes).join(', '));
    }

    if (!(outputType in validOutputTypes)) {
      throw new TypeError('Cannot convert ' + value + ' to type "' + outputType + '"; valid output types are ' + Object.keys(validOutputTypes).join(', '));
    }

    if (outputType === inputType) {
      return value;
    } else {
      return validOutputTypes[outputType](value);
    }
  }
Convert a numeric value to a specific type: number, BigNumber, or Fraction

@param {string | number | BigNumber | Fraction } value
@param {'number' | 'BigNumber' | 'Fraction'} outputType
@return {number | BigNumber | Fraction} Returns an instance of the
                                        numeric in the requested type