how to check for a certain value in pandas code example

Example 1: pandas check if value in column is in a list

df_new[df_new['l_ext'].isin([31, 22, 30, 25, 64])]

Example 2: check if value is in series pandas

In [21]: s.unique()
Out[21]: array(['a', 'b', 'c'], dtype=object)

In [22]: 'a' in s.unique()
Out[22]: True