def parse_schema(schema_file):
        """
        parses the schema file and returns the columns that are later going to represent the columns of the genometric space dataframe
        :param schema_file: the path to the schema file
        :return: the columns of the schema file
        """
        e = xml.etree.ElementTree.parse(schema_file)
        root = e.getroot()
        cols = []
        for elem in root.findall(".//{http://genomic.elet.polimi.it/entities}field"):  # XPATH
            cols.append(elem.text)
        return cols
parses the schema file and returns the columns that are later going to represent the columns of the genometric space dataframe
        :param schema_file: the path to the schema file
        :return: the columns of the schema file