Could you please post the full snippet?

c is already set to a cursor at https://github.com/python/cpython/blame/e161ec5dd7ba9355eb06757b9304019ac53cdf69/Doc/library/sqlite3.rst#L56:

    c = conn.cursor()

And the following example works fine:

    >>> import sqlite3 as s
    >>> conn = s.connect(":memory:")
    >>> c = conn.cursor()
    >>> c.execute("select 1")
    <sqlite3.Cursor object at 0x00000291A5A1F960>
    >>> c.fetchone()
    (1,)