Collates data from multiple csv files

    :param fhs: list of paths to csv files
    :param cols: list of column names to concatenate
    :param index: name of the column name to be used as the common index of the output pandas table

def fhs2data_combo(fhs,cols,index,labels=None,col_sep=': '):
    """
    Collates data from multiple csv files

    :param fhs: list of paths to csv files
    :param cols: list of column names to concatenate
    :param index: name of the column name to be used as the common index of the output pandas table 
    """

    if labels is None:
        labels=[basename(fh) for fh in fhs]
    if len(fhs)>0:
        for fhi,fh in enumerate(fhs):
            label=labels[fhi]
            data=pd.read_csv(fh).set_index(index)
            if fhi==0:
                data_combo=pd.DataFrame(index=data.index)
                for col in cols:
                    data_combo.loc[:,'%s%s%s' % (label,col_sep,col)]=data.loc[:,col]
            else:
                for col in cols:
                    data_combo.loc[:,'%s%s%s' % (label,col_sep,col)]=data.loc[:,col]    
        return data_combo
    else:
        logging.error('no fhs found: len(fhs)=0')