Add bin and edit workflow

bin/gems/facets-3.1.0/lib/standard/facets/math/sum.rb

@@ -0,0 +1,16 @@
+module Math
+
+  # Returns sum.  When a block is given, summation is taken over the 
+  # each result of block evaluation.
+  #
+  def self.sum(array) #:yield:
+    sum = 0.0
+    if block_given?
+      array.each{|i| sum += yield(i)}
+    else
+      array.each{|i| sum += i}
+    end
+    sum
+  end
+
+end