Obtains a list of HeaderElement instances referring to the header lines
parsed so far. The key member of each element references the slice of
the corresponding header line before the first ':', the val member the
slice after the first ':'. Leading and tailing white space is trimmed
off both key and val.
Obtains a list of HeaderElement instances referring to the header lines parsed so far. The key member of each element references the slice of the corresponding header line before the first ':', the val member the slice after the first ':'. Leading and tailing white space is trimmed off both key and val.