import re


def _process_code_start(script_data):
    """Converts to python a pyshell script that has ` symbol only in the beginning. An example would be:
    f = `echo 1

    :param script_data: the string of the whole script
    :return: the shellpy script converted to intermediate form
    """
    code_start_pattern = re.compile(r'^([^\n\r`]*?)([a-z]*)`([^`\n\r]+)$', re.MULTILINE)
    new_script_data = code_start_pattern.sub(r'\1start_shexe(\3)shexe(\2)shexe', script_data)
    return new_script_data