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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def find():
 """Find a local spark installation. Will first check the SPARK_HOME env variable, and otherwise search common installation locations, e.g. from homebrew """

    spark_home = os.environ.get('SPARK_HOME', None)

    if not spark_home:
        for path in [
            '/usr/local/opt/apache-spark/libexec', # OS X Homebrew
            '/usr/lib/spark/', # AWS Amazon EMR
            '/usr/local/spark/', # common linux path for spark
            '/opt/spark/', # other common linux path for spark
            # Any other common places to look?
        ]:
            if os.path.exists(path):
                spark_home = path
                break

    if not spark_home:
        raise ValueError("Couldn't find Spark, make sure SPARK_HOME env is set"
                         " or Spark is in an expected location (e.g. from homebrew installation).")

    return spark_home