title: How to only ask the user for the sign value once and not in every iteration?
body: <p>In its current state this code works. It is meant to be a transposition tool for musicians. I cant figure out how to only ask the user for the 'sign' value once and not after every successful iteration.</p>
  
  <pre class="lang-py prettyprint-override"><code>
  import time
  import sys
  usr_list = ['A','BB','B','C','C#','D','EB','E','F','F#','G','AB']
  u_list = []
  t_list = []
  
  
  
  
  def f():
      usr = int(input('Enter how many chords need to be transposed: '))
      while usr!=0:
          chord = input('\nEnter the chord that needs to be transposed: ').upper()
          if chord not in usr_list:
              print('Invalid Input')
          elif u_list.count(chord) &gt;=1:
              print('Already typed')
          else:
              usr =usr-1
              u_list.append(chord)
              print('Chords that need to be transposed are:',u_list)
      while len(u_list)&gt;0:
          chord = (u_list[0])
          sign = input('''1.Positive Transposition(+)
  2.Negative Transpostion(-)
  
  Your choice: ''')
          if sign == '1' or '+':
              sign = '+'
              time.sleep(0.2)
              print('\nPositive shift initiating')
              time.sleep(0.5)
              t_key = int(input('Enter value of transposition: '))
              chord_value = int(usr_list.index(chord))
              chord_transpose = chord_value + t_key
              if chord_transpose &gt;= 12:
                  chord_transpose = chord_transpose - 12
                  print(usr_list[chord_transpose])
              elif chord_transpose &lt; 12:
                  del u_list[0]
                  t_list.append(usr_list[chord_transpose])
                  print(u_list)
              else:
                  print('Invalid Input, Try Again!') 
          elif sign == '2' or '-':
              sign = '-'
              time.sleep(0.2)
              print('\nNegative initiating')
              time.sleep(0.5)
              t_key = int(input('Enter value of transposition: '))
              chord_value = int(usr_list.index(chord))
              chord_transpose = chord_value - t_key
              if chord_transpose &gt;= 12:
                  chord_transpose = chord_transpose + 12
                  print(usr_list[chord_transpose])
              elif chord_transpose &lt; 12:
                  del u_list[0]
                  t_list.append(usr_list[chord_transpose])
                  print(u_list)
              else:
                  print('Invalid')
          else:
              print('Invalid')
          print(t_list)
  f()
  </code></pre>
  
  <p>currently it asks the users for a number of chords they want to enter, then transposes them using a list one by one. when asking for the sign value I do not know how to only ask for that value once.</p>