title: Python 3.4.4 How to verify if a string is only made of 0 and 1
body: <p>I'm doing a binary to decimal converter in python 3.4.4 and it's pretty much finished except for the fact that I would like to check that the binary number entered by the user is indeed a binary number (check if the string is only made of o and 1) but I'm unsure what to do.</p>
  
  <p>here's the program:</p>
  
  <pre><code>binary=input("Enter a binary number") 
  bit=len(binary)
  result=0
  power=0
  while bit&gt;0:
      result=result+int(binary[bit-1])*2**power
      bit=bit-1
      power=power+1
  print(binary, " in decimal is equal to ", result, sep="")
  </code></pre>
  
  <p>hopefully someone can help me &lt;3</p>