Using `peek` method on enumerator consumes the row

[thelibrarian]

Hi,

When using the enumerator form of OSV, if you call the #peek method, it moves the current position forward to the next row, so that the "peeked" row is now no longer yielded or returned when iterating the enumerator.

Current behaviour:

irb(main):001> require 'osv'
true
irb(main):002> require 'stringio'
false
irb(main):003> s = StringIO.new("test_1,test_2\r\nfoo,bar\r\n")
#<StringIO:0x000000012498b960>
irb(main):004> e = OSV.for_each(s)
#<Enumerator: OSV:for_each(#<StringIO:0x000000012498b960>, has_headers: true, col_sep: ,, quote_char: ", nil_string: , result_type: hash, flexible: false, trim: , ignore_null_bytes: false, lossy: false)>
irb(main):005> e.peek.keys
[
    [0] "test_1",
    [1] "test_2"
]
irb(main):006> e.each { |r| puts r['test_1'] }
nil

Expected behaviour:

irb(main):001> require 'osv'
true
irb(main):002> require 'stringio'
false
irb(main):003> s = StringIO.new("test_1,test_2\r\nfoo,bar\r\n")
#<StringIO:0x000000012498b960>
irb(main):004> e = OSV.for_each(s)
#<Enumerator: OSV:for_each(#<StringIO:0x000000012498b960>, has_headers: true, col_sep: ,, quote_char: ", nil_string: , result_type: hash, flexible: false, trim: , ignore_null_bytes: false, lossy: false)>
irb(main):005> e.peek.keys
[
    [0] "test_1",
    [1] "test_2"
]
irb(main):006> e.each { |r| puts r['test_1'] }
foo
nil

From Ruby documentation for Enumerator#peek

Returns the next object in the enumerator, but doesn’t move the internal position forward.