public static Fraction fromString(final String str) {
    checkArgument(str != null);
    return fromFloat(parseFloat(str));
  }
Parse a string representing a fraction.

@param str A string representing a valid positive number strictly between 0 and 1.
@return The parsed double.
@throws IllegalArgumentException if the provided string is {@code null}.
@throws IllegalArgumentException if the string is either not a number, or not a fraction
util/src/main/java/org/hyperledger/besu/util/number/Fraction.java