# Pastebin qimE8AHP
from pandas import DataFrame
data = {'col1': [1, 2, None], 'col2': [3, None, 4]}
print(DataFrame(data))
print()
print(DataFrame(data, dtype=object))

   col1  col2
0   1.0   3.0
1   2.0   NaN
2   NaN   4.0

   col1  col2
0     1     3
1     2  None
2  None     4