How to use Ruby BioSamtools for SNP finding on .bam and .sam files? Does my code call variants or not, I am not sure...

#!/usr/bin/ruby # making script executable

require 'bio-samtools' # calling rubygem

bam=Bio::DB::Sam.new(:bam=>"my.bam",:fasta=>'fake.fa') # creating bam object
bam.open
bam.index

bam.mpileup do |pileup| # calling variants??? how to call them on a bam or sam object
puts pileup.consensus


bam.flag_stats() # getting statistics and plots
bam.plot_coverage()
bam.close

end