'NoneType' object has no attribute 'drop' code example

Example 1: AttributeError: 'NoneType' object has no attribute 'dropna'

import pandas as pd
file = pd.read_csv("/my/path/to/spreadsheet.csv", index_col=0)
file.dropna(how="any", inplace=True)
file = file.fillna("", inplace=False)
print(file)

Example 2: 'NoneType' object has no attribute 'attname'

super().__init__(*args, **kwargs)

Example 3: AttributeError: 'Database' object has no attribute 'remove'

def remove_item(self):
        db.remove(self.selected_item[0])
        self.clear_text()
        self.populate_list()

Example 4: AttributeError: 'NoneType' object has no attribute

node = child.find('EmentaMateria')
if node is not None:
    ementa = node.text
else:
    ementa = None