import pandas as pd

def signals(data: pd.DataFrame) -> pd.Series:
    """
    Calculate swing trading signals based on Internal Bar Strength Band strategy.
    
    Returns a Series with 'L' for long signals and 'N' otherwise.
    """
    ma_200 = data['Close'].rolling(window = 200).mean()

    rolling_high_minus_low = (data['High'] - data['Low']).rolling(window = 25).mean()
    rolling_high = data['High'].rolling(window = 10).max()
    lower_band = rolling_high - 2.5 * rolling_high_minus_low

    ibs = (data['Close'] - data['Low']) / (data['High'] - data['Low'])

    signals = (
        (data['Close'] > ma_200) & 
        (data['Close'] < lower_band) & 
        (ibs < 0.3)
    ).apply(lambda condition: 'L' if condition else 'N')
    return signals