Python-Remove rows based on lack of character
<p>I would like to remove a row from my file if it contains a letter other than A, C, G, or T.  So that ['TC', 'CY', 'GS', 'GA', 'CT'] will become ['TC', 'GA', 'CT']. </p>

<p>The files will have an unknown number of rows and will contain patterns of 2 or more letters in any order.  In addition, I do not know the other letters that are present (Y or S or something else).</p>

<p>How would I go about setting up a program for this preferably in Python?  I already can import my file and read the rows. </p>

<p>Thanks!</p>
