Error in Python Code

[ErnestTBass]

The following python code gives an error.

%reload_ext nb_black

import yfinance
import pandas as pd
import numpy
import matplotlib.pyplot as plt

portfolio_composition = [("MSFT", 0.5), ("AAPL", 0.2), ("GOOG", 0.2)]
returns = pd.Dataframe({})

for t in portfolio_composition:
    name = t[0]
    ticker = yfinance.Ticker(name)
    data = ticker.history(interval="id")
    start = "2010-01-01", end = "2019-12-31"

    data["return_%s"(name)] = data["Close"].pct_change(1)
    returns.join(data[["returns_%s" % (name)]], how="outer").dropna()

It is the start line and the error is now shown:

Error:
File "<ipython-input-1-c1daa2af4c39>", line 15
    start = "2010-01-01", end = "2019-12-31"
           ^
SyntaxError: can't assign to literal

I am not sure what is incorrect. At first it gave me an error on the line:

returns = pd.Dataframe({})

It did not like the dataframe. An attribute was missing.

But now it is throwing this error.

What bis wrogn with the syntax?

Any help appreciated. Thanks in advance.

Respectfully,

ErnesrtTBass