# Define a method that returns a boolean indicating whether any two elements in the argument (an array) sum to 0.

def two_sum_to_zero?(arr)
  i = 0
  while i < arr.length #thereby iterating through the array
    num_one = arr[i]
    j=i+1
    while j <arr.length
      num_two = arr[j]
      if num_one + num_two == 0
        return true
      else
        return false
      end
      j=j+1
    end
    i=i+1
  end
end


puts two_sum_to_zero?([1,-1])
puts two_sum_to_zero?([1,2,3,4])