title: Strip part of string before a particular character, in a case where the character occurs multiple times
body: <p>I need to strip the string off the part that occurs before the character <code>':'</code>, where <code>':'</code> may occur multiple times.
  For Example:</p>
  
  <pre><code>input: 'Mark: I am sending the file: abc.txt'
  output: 'I am sending the file: abc.txt'
  </code></pre>
  
  <p>The function I have is this (Python code)</p>
  
  <pre><code>def process_str(in_str):
      str_list = in_str.split(':')[1:]
      out_str = ''
      for each in str_list:
          out_str += each
      return out_str
  </code></pre>
  
  <p>The output I am getting is <code>'I am sending the file abc.txt'</code> without the second <code>':'</code>.
  Is there a way to correct this? 
  Also can this code be made more efficient in time and space complexity?</p>