def return_outlier_limits(df,column):
    """
    Function calculates Interquartile Range (IQR) in order to return upper and lower limits after which to consider a value an outlier. 
        A limit is defined as 1.5 times the IQR below Quartile 1 (Q1) or above Quartile 3 (Q3).
    
    Args:
        df - Pandas DataFrame 
        column - Column of DataFrame with the aforementioned outliers, input as a string.
    Output:
        List with lower and upper outlier limits.
    """
    
    # The .describe() method for Pandas DataFrames outputs a Pandas Series; index number 4 corresponds to 
    # Quartile 1, index number 6 to Quartile 3. The Inter-Quartile Range (IQR) is then calculated as Q3 - Q1.
    Q1 = df[column].describe()[4]
    Q3 = df[column].describe()[6]
    IQR = float(Q3 - Q1)
    
    # An outlier threshold is calculated as 1.5 times the IQR. 
    outlier_threshold = 1.5 * IQR
    lower_limit = Q1 - outlier_threshold
    upper_limit = Q3 + outlier_threshold
    
    limits = [lower_limit, upper_limit]
   
    return limits