Given a string named DNA and a second string named valid, build a dictionary named counts that contains the counts of all characters in DNA that are present in valid. For example, if DNA is a name for "ACGTU" and valid is a name for "ACGT", then counts would refer to a dictionary ${\{}^{\text{'}}{A}^{\text{'}}$:$1,{?}^{\text{'}}{C}^{\text{'}}$:$1,{?}^{\text{'}}{?}^{\text{'}}$:$1,{?}^{\text{'}}{T}^{\text{'}}$:$1\}$

Additional Notes: valid and DNA should not be modified