title: Find a regex match and replace start
body: <p>I have huge amount of special strings containing coordinates and other information.</p>
  
  <p>What I need to do is find a matching string that starts with a <code>G1</code> and ends with <code>F4500</code>, afterwards in that matching string I have replace the <code>G1</code> with a <code>G0</code>.</p>
  
  <p>Example:</p>
  
  <p>Initial: <code>G1 X95.090 Y104.910 F4500</code></p>
  
  <p>Modified: <code>G0 X95.090 Y104.910 F4500</code> </p>
  
  <p>I was breaking my head over this for quite some time now and can't seem to figure it out.</p>