from pandas import DataFrame, Series

def signals(data: DataFrame) -> Series:
    """
    Generate signals for entering a long trade when the market's 
    close price is lower for 3 consecutive days.

    Returns a Series with 'L' for long signals and 'N' otherwise.
    """
    lower_close = data['Close'] < data['Close'].shift(1)
    return (lower_close & lower_close.shift(1) & lower_close.shift(2)).apply(lambda x: 'L' if x else 'N')