input: Write a python function to load a CSV file, split it into features and target, and train a linear regression model using sklearn.
  assert train_linear_regression("housing_data.csv").coef_.shape[0] == 3  # Assuming the CSV has 3 feature columns.
  assert isinstance(train_linear_regression("housing_data.csv"), LinearRegression)
output: def train_linear_regression(file_path):
      import pandas as pd
      from sklearn.linear_model import LinearRegression
  
      # Load the CSV file
      data = pd.read_csv(file_path)
      
      # Assuming the last column is the target and the rest are features
      X = data.iloc[:, :-1]
      y = data.iloc[:, -1]
  
      # Train the linear regression model
      model = LinearRegression()
      model.fit(X, y)
      
      return model