The set of all strings with twice as many 0's as 1's

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I have to create a PDA that accepts strings with twice as many 0's as 1's. So far I have decided to create one which accepts via empty state:

(q0, 0, Z0) - (q1, 0)

(q0, 1, Z0) - (q1, 11)

(q1, 1, 1) - (q1, 111)

(q1, 0, 1) - (q1, e)

Now when I get to this situation I am not sure how to proceed

(q1, 1, 0) - ?