code: public static byte sum(byte[] self, byte initialValue) {
          byte s = initialValue;
          for (byte v : self) {
              s += v;
          }
          return s;
      }
docs: Sums the items in an array, adding the result to some initial value.
  <pre class="groovyTestCase">assert (5+1+2+3+4 as byte) == ([1,2,3,4] as byte[]).sum(5 as byte)</pre>
  
  @param self         an array of values to sum
  @param initialValue the items in the array will be summed to this initial value
  @return The sum of all of the items.
  @since 2.4.2