title: Python Binary String Loop
body: <p>The question on my assignment is as follows:</p>
  
  <blockquote>
    <p>Write a function that takes, as an argument, a string, identified by the variable <code>aString</code>. If the string only contains digits 0 and 1, return the string formed by concatenating the argument with the string "is a binary string." Otherwise, return a string indicating the length of the argument, as specified in the examples that follow. Name this function <code>AmIBinary(aString)</code>. </p>
  </blockquote>
  
  <p>I am having trouble figuring out how to form a loop which searches through a string and determines whether or not the string is a binary string. I understand how to get the length of a string, I just don't understand how to figure out if it is a binary string. </p>