class Calculator

# File lib/zhalo_calculator.rb, line 3
def self.add(opl, opr)
        sum = opl.to_i + opr.to_i
        "result: " + sum.to_s
end

# File lib/zhalo_calculator.rb, line 23
           def self.commands()
        "available commands: add subtract multiply divide"
end

# File lib/zhalo_calculator.rb, line 18
def self.divide(opl, opr)
        result = opl.to_i / opr.to_i
        "result: " + result.to_s
end

# File lib/zhalo_calculator.rb, line 13
def self.multiply(opl, opr)
        result = opl.to_i * opr.to_i
        "result: " + result.to_s
end

# File lib/zhalo_calculator.rb, line 8
def self.subtract(opl, opr)
        diff = opl.to_i - opr.to_i
        "result: " + diff.to_s
end