What is the problem with slicing a dataframe using a single label for both the row and column?

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The problem with slicing a dataframe using a single label for both the row and column is that it may return a scalar value instead of a dataframe. This is because pandas will interpret the single label as a request for a single value, rather than a subset of the dataframe. If the label is not present in the dataframe, it will raise a KeyError.