Pipe Function to several columns

pipe_several.py

# Instead of repeating yourself
df["started_at"] = pd.to_datetime(df["started_at")
df["ended_at"] = pd.to_datetime(df["ended_at"])

# Leverage the power of pipe
df.pipe(
    lambda x: x.assign(
        **{  # Apply same function to both columns in one go
            col: pd.to_datetime(x[col], format="%Y-%m-%d %H:%M:%S")
            for col in ["started_at", "ended_at"]
        }
    )
)