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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _remove_nonascii(self, df):
 """Make copy and remove non-ascii characters from it."""


    df_copy = df.copy(deep=True)
    for col in df_copy.columns:
      if (df_copy[col].dtype == np.dtype('O')):
        df_copy[col] = df[col].apply(
          lambda x: re.sub(r'[^\x00-\x7f]', r'', x) if isinstance(x, six.string_types) else x)

    return df_copy