Adding multiple numbers
Remove ambiguous test and refactoring production code
Allow to use newline separator
Allow to use custom separator
Extract class number extractor
Refactor sum logic
Move method sum to array prototype
Throw error when adding negatives
Move method negatives to array prototype
Extract method validateNegatives
Create NumberExtractor decorator to validate negatives
Ignore elements bigger than 1000
Allow delimiter of any length
Allow multiple delimiters
Allow multiple delimiters of any length
Added a fluent builder for String Calculator
Refactoring to accept generic validators and filters