import re


def clean_abstract_string(abstract):
    """Returns a string cleaned of initiial '"@ ' and trailing ' @"@en'.
    ' @ ' within the string are replaced by ' '.
    '\"' within the string are replaced by '"'
    tab is replaced by ' '

    Arguments:
    abstract - the abstract string
    """
    abstract = re.sub(r'^"@ ', '', abstract)
    abstract = abstract.replace('"@en', "")
    abstract = abstract.replace('@', '')
    abstract = re.sub(r' ( )+', ' ', abstract)
    abstract = abstract.replace('\\"', '"')
    abstract = abstract.replace('\t', ' ')
    return abstract