Regex: Perl to Python

[Fillmore]

Hi, I'm trying to move away from Perl and go to Python.
Regex seems to bethe hardest challenge so far.

Perl:

while (<HEADERFILE>) {
    if (/(\d+)\t(.+)$/) {
        print $1." - ". $2."\n";
    }
}

into python

pattern = re.compile(r"(\d+)\t(.+)$")
with open(fields_Indexfile,mode="rt",encoding='utf-8') as headerfile:
    for line in headerfile:
        #sys.stdout.write(line)
        m = pattern.match(line)
        print(m.group(0))
    headerfile.close()

but I must be getting something fundamentally wrong because:

Traceback (most recent call last):
  File "./slicer.py", line 30, in <module>
    print(m.group(0))
AttributeError: 'NoneType' object has no attribute 'group'


 why is 'm' a None?

the input data has this format:

         :
     3  prop1
     4  prop2
     5  prop3

Thanks
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