Return boolean ndarray denoting duplicate values.
first : Mark duplicates as True except for the first occurrence.
last : Mark duplicates as True except for the last occurrence.
False : Mark all duplicates as True.
Examples
>>> pd.array([1, 1, 2, 3, 3], dtype="Int64").duplicated()
array([False, True, False, False, True])
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https://pandas.pydata.org/pandas-docs/version/2.3.0/reference/api/pandas.api.extensions.ExtensionArray.duplicated.html