BigInteger, BigDecimal and BigRational are now final

src/BigDecimal.php

@@ -7,7 +7,7 @@ use Brick\Math\Internal\Calculator;
 /**
  * Immutable, arbitrary-precision signed decimal numbers.
  */
-class BigDecimal extends BigNumber implements \Serializable
+final class BigDecimal extends BigNumber implements \Serializable
 {
     /**
      * The unscaled value of this decimal number.

src/BigInteger.php

@@ -10,7 +10,7 @@ use Brick\Math\Internal\Calculator;
  * All methods accepting a number as a parameter accept either a BigInteger instance,
  * an integer, or a string representing an arbitrary size integer.
  */
-class BigInteger extends BigNumber implements \Serializable
+final class BigInteger extends BigNumber implements \Serializable
 {
     /**
      * The value, as a string of digits with optional leading minus sign.

src/BigRational.php

@@ -7,7 +7,7 @@ namespace Brick\Math;
  *
  * This class is immutable.
  */
-class BigRational extends BigNumber implements \Serializable
+final class BigRational extends BigNumber implements \Serializable
 {
     /**
      * The numerator.