<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def PyDbLite_to_csv(src,dest=None,dialect='excel'):

 """Convert a PyDbLite base to a CSV file
 src is the PyDbLite.Base instance
 dest is the file-like object for the CSV output
 dialect is the same as in csv module"""

    import csv
    fieldnames = ["__id__","__version__"]+src.fields
    if dest is None:
        dest = open(os.path.splitext(src.name)[0]+'.csv','w')
    w = csv.DictWriter(dest,fieldnames,dialect)
    first = dict([(f,f) for f in fieldnames])
    w.writerow(first) # first row has the field names
    for r in src:
        if not "__version__" in r:
            r["__version__"] = 0
        w.writerow(r)
    dest.close()