input: Write a function to store and print the multiplication table of a given number. If the given number is negative, return an empty string.
  assert print_multiplication_table(5)=='5 x 1 = 5\n5 x 2 = 10\n5 x 3 = 15\n5 x 4 = 20\n5 x 5 = 25\n5 x 6 = 30\n5 x 7 = 35\n5 x 8 = 40\n5 x 9 = 45\n5 x 10 = 50\n'
  assert print_multiplication_table(0)==''
  assert print_multiplication_table(-5)==''
  assert print_multiplication_table(7)=='7 x 1 = 7\n7 x 2 = 14\n7 x 3 = 21\n7 x 4 = 28\n7 x 5 = 35\n7 x 6 = 42\n7 x 7 = 49\n7 x 8 = 56\n7 x 9 = 63\n7 x 10 = 70\n'
output: def print_multiplication_table(number):
      if number < 0:
          return ''
      result = ''
      for i in range(1, 11):
          result += f'{number} x {i} = {number * i}\n'
      return result.strip()