# 0207.py

def dnanumero (x):
  sost=dict(g=0,a=1,c=2,t=3)
  return sost.get(x.lower(),x)

g='TGAATGCTAC'
print ([dnanumero(x) for x in g])
# [3, 0, 1, 1, 3, 0, 2, 3, 1, 2]