code: def fit_linear(X, y):
      """
      Uses OLS to fit the regression.
      """
      model = linear_model.LinearRegression()
      model.fit(X, y)
      return model
  
file_path: yellowbrick/yellowbrick/bestfit.py
imports: import numpy
  import matplotlib.pyplot
  from sklearn import linear_model
  from sklearn.preprocessing import PolynomialFeatures
  from sklearn.pipeline import make_pipeline
  from sklearn.metrics import mean_squared_error
  from operator import itemgetter
  from yellowbrick.style.palettes import LINE_COLOR
  from yellowbrick.exceptions import YellowbrickValueError
label_desc: Use image node_id 3 for calling a global function with example usage: fit_linear(X, y) and returns: model